In an exclusive sit-down with PEOPLE, Wilkinson calls the memoir – and Madison – "irrelevant."

Madison, 35, is not the first of Hugh Hefner's girlfriends to tell her side of the story. Wilkinson's 2010 memoir, Sliding into Home – which she began writing not long after leaving the Playboy Mansion to begin a life with former NFL wide receiver Hank Baskett – painted a much more flattering (and racy) picture of the life of a Playboy bunny, and of Hefner, now 89, himself.

Former The Girls Next Door stars Kendra Wilkinson and Holly Madison fell out years ago. But with their feud reignited – thanks to Madison's juicy new tell-all memoir, Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny – we're wondering now more than ever: What was life really like in the mansion?

Holly Madison's tell-all new memoir, Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny, has caused no shortage of drama, pitting bunny against bunny. The former Playboy model says writing the memoir, however, was the "embarrassing" part – rather than the headline-making aftereffects.

But Wilkinson tells PEOPLE Now that Hefner, 89, is right to accuse Madison of rewriting history in Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny. What's more, she believes Madison has an ulterior motive for alleging tales of lies, manipulation and suicidal thoughts at the Playboy Mansion in her new memoir.

Kendra Wilkinson has lived in the Playboy Mansion, gotten hitched to a pro football player, starred in a handful of reality shows, welcomed two kids and made it through the other side of a sordid cheating scandal – and that's all just in her first 30 years.

As Kendra celebrates her birthday this week, we look back at her brashest, Splash-iest moments on camera and off.